Wildfires disproportionately affected jaguars in the Pantanal

The Pantanal wetland harbours the second largest population of jaguars in the world. Alongside climate and land-use changes, the recent mega-fires in the Pantanal may pose a threat to the jaguars’ long-term survival. To put these growing threats into perspective, we addressed the reach and intensity of fires that have affected jaguar conservation in the Pantanal ecoregion over the last 16 years. The 2020 fires were the most severe in the annual series, burned 31% of the Pantanal and affected 45% of the estimated jaguar population (87% of these in Brazil); 79% of the home range areas, and 54% of the protected areas within home ranges. Fires consumed core habitats and injured several jaguars, the Pantanal’s apex predator. Displacement, hunger, dehydration, territorial defence, and lower fecundity are among the impacts that may affect the abundance of the species. These impacts are likely to affect other less mobile species and, therefore, the ecological stability of the region. A solution to prevent the recurrence of mega-fires lies in combating the anthropogenic causes that intensify drought conditions, such as implementing actions to protect springs, increasing the number and area of protected areas, regulating fire use, and allocating fire brigades before dry seasons.


Relationship of the year and project region with fire occurrence
We used a two-way ANOVA to evaluate the effect of year, project region, and ID on realtime fire occurrence within jaguar HRs (during real-time monitoring) and jaguar HRs (HRs compared across all years). The interaction between year and project region on fire occurrence was the most plausible model, since it generated the smallest residuals (Table S4). However, a major limitation in the real-time analysis was the unequal distribution of jaguar HRs in space and time. Years without monitoring (2007,(2017)(2018)(2019)(2020) or with sparse or clustered monitoring (2005)(2006)(2008)(2009), and 2016) seemed to neglect or underestimate the impact of fires on the overall jaguar HRs (Figs. S12-S15). Conversely, the main approach used here (using 48 home ranges of resident jaguars across multiple years Figs.2 and 3 in the main text) was more representative in space and time.

Additional details about the cumulative impacts in the UPRB and Pantanal (Discussion)
An assessment of the integrity risk of aquatic ecosystems identified hydroelectric power plants, urbanization, and agribusiness as the top three stressors among 13 anthropic activities impacting the Upper Paraguay River Basin (UPBR) 1 . Environmental degradation (e.g., deforestation, erosion, sewage), economic activities (e.g., agriculture, mining), and infrastructure (e.g., dams, hydroelectric power plants, waterways, gas pipelines) are associated with the demand and pressure of an increasing human population in the UPRB. These environmental damages can interfere with drainage dynamics, flood pulses, and drought extent and, consequently, impact ecological richness, biodiversity, and ecosystem services [1][2][3][4][5][6] .
The Pantanal occupies 38% of the UPRB 7 , and the water that drains into the lowlands and floods in the Pantanal comes from springs in the highlands 6,8 . Thus, the removal of the vegetation cover that protects these springs in the neighbouring biomes within the UPRB (Cerrado, Amazonia, Atlantic Forest, and Chaco) 9 impacts the drainage, water quality, and hydrological regime of the Pantanal 1,4-7 . Deforestation, mining activities 2,10 and hydroelectric power plants (total ≈ 180, 47 of them installed or in operation and 133 planned) 11 change water quality and flow, causing erosion, river sedimentation 2,9 , and reduction of outflow (up to 100% in drier years) and nutrient transport to the Pantanal floodplains 12,13 . Additional problems include reduced light, which is causing a decline or disappearance of aquatic plants and photosynthetic algae 1 , hypoxia and a consequent cascade effect, such as reduced food availability for fish 1 and bioaccumulation of toxic mercury 10,14 .
The implementation of a waterway on the Paraguay River, hydroelectric power plants, railroads, and highways have long been debated in academia, legal courts, and by stakeholders 2,15-20 . Overwhelming evidence of negative impacts has barred or reduced the development of large enterprises, such as the construction of a 3,440 km 2 north-south waterway from Cáceres (Brazil) to Nueva Palmira (Uruguay) and large hydroelectric power plants 2,15-18 . However, a subterfuge often used by stakeholders in many new enterprises is to propose several small hydroelectric plants, ports, or relatively short canalization projects as low-impact alternatives, without considering their cumulative impacts 21 . In addition, the supposed small individual impact is often used as an excuse to limit the decision-making to a smaller group of stakeholders 16,22 , the so-called "tyranny of small decisions" 16,23 . And the quality of many Environmental Impact assessments in Brazil lacks scientific rigor 24 . The impact of the cumulative effects of small ventures can be only avoided by adopting a holistic perspective in a process involving scientists with relevant subject matter expertise, planners, politicians, and other social actors 16,23 in in-depth studies, with impartial evaluation and discussions (e.g., using a Strategic (or Integrated) Environmental Assessments (SEA) or equivalent approaches 11,21,[25][26][27]. Successful regulation based on laws 27 and updated SEAs for the Pantanal 1,11 , through a transparent and plural engagement of civil society, could bring invaluable advances for conservation and provide science-based guidance to attain sustainability 2,11,28,29 . See Fig.4 in the main text. Fig.S1.Top: Comparative histograms of yearly fire available datasets, based on MODIS satellites indicating occurrence of fire foci (INPEfire_foci) 30 , derived proportion of burned area (FIRMS_Perc_fire_Pantanal) 31,36 and burned area based on LANDSAT satellites (MapBiomas_fire_Km 2 ) 32 . Bottom: The continuous lines correspond to the minimum annual river depths (minimum quotas in meters from 1985 to 2020) at six Pantanal gauge stations in the Paraguay River. The dashed lines in the same colours correspond to the respective historical medians (HM) at each station 33,34 . The histograms correspond to the MapBiomas 5.        37 . Note that 28 years had estimates below the historical average, with five years (1980,1993,1994,2004,2012) having estimates more than 20% below the historical average 37 . Data acquired for 2020 was limited until October.     This projection allowed us to explore the impacts of fire on jaguar HRs for years in which tracking data were unavailable (as was the case for 2020) (see Table S4).      35,42 . Cattle livestock is the most abundant economic activity. It continues to increase in Pantanal areas of both states, although the number of cattle and pastures in the Cerrado has decreased (see Fig.S18). Nonetheless, agriculture was the anthropic activity with the highest percentage growth (MapBiomas data) 35 . Cattle livestock is still the most abundant economic activity, but the area occupied by agriculture (particularly soybean plantations) is increasing 35 .  Table S3.  49 . Data used in the analyses are shown in Table S5.  Table  S6).

Supplementary Tables
Tab.S1. Areas and percentages of Brazilian protected areas (PAs) in the Pantanal, Uplands, and within Paraguay River Basin (UPRB). Brazilian UPRB corresponds to the basin area in Brazil. Total UPRB corresponds to the total basin area (multiple countries), and Total PRB corresponds to the entire Paraguay River Basin (PRB). Note that all non-resident jaguars had DOF area < 5, except for individual 81 (which had the largest amount of tracking locations in the dataset); however, observation of the variograms showed that this individual is a non-resident (see Fig.S21).